recent developments of sub-mm wave ......and backward wave oscillator (bwo) covering the frequency...

RECENT DEVELOPMENTS OF SUB-MM WAVE SPECTROMETERIN LILLE

R. A. MOTIYENKO L. MARGULES, Laboratoire PhLAM, CNRSUMR 8523, Universite de Lille 1, 59655 Villeneuve d’Ascq Cedex,France; E. A. ALEKSEEV, Institute of Radio Astronomy of NASU,Chervonopraporna 4, 61002 Kharkov, Ukraine.

Recent developments of microwave spectrometer in Lille will be presented. The spectrom-eter utilizes two different types of radiation source: the solid states sources (frequencymultiplier chains based on Schottky diodes) covering the frequency range 150 - 530 GHzand backward wave oscillator (BWO) covering the frequency range 580 - 660 GHz. Bothtypes of sources have several advantages in their application. Solid state sources arecompact and simple in use, but they provide less output power in sub-mm wave rangecompared to BWOs. Using a BWO phase locked to a DDS-based reference synthesizerone can obtain very fast frequency scan, but the BWO itself is quite difficult instrument towork with (high voltage, high magnetic field, water cooling etc). The application of thesetwo synthesizers to millimeter and sub-millimeter wave survey spectra records of severalmolecules of astrophysical interest (methyl formate, methanol, formamide, aminopropa-nenitrile, aziridine) will be discussed.This work is supported by ANR-08-BLAN-0054 and ANR-08-BLAN-0225. The support ofUniversite de Lille 1 and le Programme National de Physique Chimie du Milieu Interstel-laire is gratefully acknowledged.

Presentation mode: poster

SUBTERAHERTZ SOURCE WITH SUPER CLEAN SPECTRUM:NEW POSSIBILITY FOR SUB-DOPPLER SPECTROSCOPY

M.Yu. TRETYAKOV, A.P. Shkaev, A.M. Kiselyev, S.B. Bo-drov, A.V. Andrianov, D.S. Makarov, Institute of AppliedPhysics, Russian Academy of Sciences, 46 Uljanova str., Nizhniy Nov-gorod, 603600, Russia.

Laser frequency combs generated by femtosecond lasers have opened new horizons in theaccuracy of frequency and time standards. The laser combs provide the most accuratefrequency measurement from the radio frequency to near ultraviolet range with the useof nonlinear sum and difference frequency generation. To the best of our knowledge wewere the first to develop frequency stabilization system for primary radiation source ofsubterahertz range, which allows phase locking against the equidistant components of abroad spectrum produced by a femtosecond laser. 100-GHz backward wave oscillator wasused as the primary source of radiation for the system workability demonstration. Theoptical frequency comb was produced by the radiation of a Ti:Sapphire femtosecond laser.The laser pulse repetition rate was stabilized against microwave synthesizer. The opticalto terahertz down conversion of the laser pulse train and its mixing with subterahertzradiation has been performed at a Schottky diode. This work provides the opportunityof creating a principally new generation of frequency synthesizers with the desiredpower and phase noise a few orders of magnitude lower than that of their traditionalanalogues. Such sources are highly requested for sub-Doppler spectroscopy because sig-nal to nose ratio of observed lines directly depends on a spectral purity of radiation source.

The work was partly supported by Russian Fundation for Basic Research.

1. M.Yu. Tretyakov, A.P. Shkaev, A.M. Kiselyev, S.B. Bodrov, A.V. Andrianov, D.S.Makarov, JETP letters, 91 222-225 (2010).


POUND-DREVER-HALL-LOCKED FREQUENCY STABILIZEDCAVITY RING-DOWN SPECTROMETER

A. CYGAN, D. LISAK, P. MASLOWSKI, K. BIELSKA,S. WOJTEWICZ, J. DOMYSLAWSKA, R. S. TRAWINSKI,R. CIURYLO, Instytut Fizyki, Uniwersytet Mikolaja Kopernika, ul.Grudziadzka 5, 87-100 Torun, Poland; H. ABE, National Metrology In-stitute of Japan (NMIJ), AIST, Tsukuba Central 3, Tsukuba 305-8563,Japan; J. T. HODGES, National Institute of Standards and Technol-ogy, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.

It was demonstrated that the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) developed at NIST [1,2] is useful for measurements of spectral line shapes andline intensities. In this technique the optical path length of the ring-down cell is activelystabilized by locking it to a frequency-stabilized reference HeNe laser with a low-bandwidthservo. Such a setup compensates for thermal drift of the cavity modes and assures long-term stability of the spectrum frequency axis. The probe laser is mode-matched and lockedto the TEM00 mode of the cavity and only one of the cavity modes is excited at a time,yielding single exponential ring-down signals. The frequency tuning of the spectrometeris realized by relocking the probe laser to consecutive TEM00 modes of the cavity and bytuning the HeNe laser frequency, which shifts the whole comb of the cavity modes. See[1,2] for details.We used the Pound-Drever-Hall (PDH) technique to lock the probe laser to the ring-down cavity in our new FS-CRDS setup, built at UMK operating at wavelengths near690 nm. Similar locking scheme was recently used by Martinez et al. [3] in their CRDSsetup without active stabilization of the cavity frequency comb. Comparison of the systemperformance between both locking schemes, with and without PDH lock, will be presented.Here we show initial results of weak oxygen B -band line shapes measurements obtained atlow pressures with the new CRDS system. The new locking scheme increases the signal-to-noise ratio of the measured spectra fivefold compared to the previous system for the samewavelength [4]. The PDH lock reduces the probe laser line width and enables the injectionof more light into the ring-down cavity. Rapid relocking of the laser after ring-down eventalso enables a significant increase in the data acquisition rate. Thus with a tenfold increasein the numb er of ring-down signals acquired, the time to acquire a spectrum is still threetimes shorter with the PDH lock compared to the previous method.

The research is part of the program of the National Laboratory FAMO in Torun, Poland andsupported by the Polish MNISW Projects No. N N202 1255 35 and N N202 1489 33, and by GrantJMR UMK 503-F.

[1] J. T. Hodges, H. P. Layer, W. W. Miller, and G. E. Scace, Rev. Sci. Instrum. 75, 849(2004).[2] J. T. Hodges and R. Ciurylo, Rev. Sci. Instrum. 76, 023112 (2005).[3] R. Z. Martinez, M. Metsala, O. Vaittinen, T. Lantta, and L. Halonen, J. Opt. Soc.Am. B 23, 727 (2006).[4] D. Lisak, P. Maslowski, A. Cygan, K. Bielska, S. Wojtewicz, M. Piwinski, J. T. Hodges,R. S. Trawinski, and R. Ciurylo, Phys. Rev. A 81, 042504 (2010).


HIGH-RESOLUTION FREQUENCY-STABILIZED CAVITY RING-DOWN SPECTROSCOPY OF THE OXYGEN B-BAND TRANSI-TIONS AT LOW PRESSURES

D. LISAK, P. MASLOWSKI, A. CYGAN, K. BIEL-SKA, S.WÓJTEWICZ, M. PIWINSKI, R. S. TRAWINSKI,R. CIURYLO, Instytut Fizyki, Uniwersytet Mikolaja Kopernika, ul.Grudziadzka 5, 87-100 Torun, Poland; J. T. HODGES, National In-stitute 01 Standards and Technology, 100 Bureau Drive, Gaithersburg,Maryland 20899, USA.

Line shapes and intensities ofself-broadened oxygen b1E:(v = 1) +- X3E;(v = 0) band(B-band) transitions were investigated. Data were acquired using the frequency-stabilizedcavity ring-down spectroscopy technique [1,2] under relatively low pressure conditions.Line-shape parameters describing collisional broadening and shifting are given. The ob-served line narrowing is interpreted as Dicke narrowing or the speed dependence of col-lisional broadening. The influence of the choice of the line shape model used for dataanalysis on resulting intensities and line-shape coefficients is also discussed, see Ref. [3]for details. We indicate the importance of the line-narrowing effect which, if neglected,changes the experimentally determined collisional broadening coefficients by up to 48% atpressures below 3.3 kPa. We report measured line intensities with relative uncertaintiesbelow 0.7% and compare these measurements to available data in HITRAN database.

The research is part of the program of the Natiollal Laboratory FAMO in Tormí, Poland andsupported by thc Polish MNISW Projccts No. N N202 1255 35 and N N202 1489 33, and by GrantJMR UMK 503-F.

[1] J. T. Hodges, H. P. Layer, W. W. Miller, and G. E. Scace, Rev. Sci. Instrum. 75,849(2004).[2] J. T. Hodges and R. Ciurylo, Rev. Sci. Instrum. 76,023112 (2005).[3]D. Lisak, P. Maslowski, A. Cygan, K. Bielska, S. Wójtewicz, M. PiwiIÍski, J. T. Hodges,R. S. Trawiñski, and R. Ciurylo, Phys. Rev. A 81, 042504 (2010).


MID INFRARED CW CAVITY RING DOWN SPECTROSCOPY OFMOLECULAR IONS USING AN OPTICAL PARAMETRIC OSCILLA-TOR

JOSEPH S. GUSS, HARALD VERBRAAK, and HAROLDLINNARTZ, Sackler Laboratory for Astrophysics, Leiden Observatory,Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Nether-lands.

A sensitive infrared detection scheme is presented, in which continuous wave cavity ringdown spectroscopy (CRDS) is used to record rovibrational spectra of molecular ions andionic complexes in direct absorption through an expanding planar plasma. A cw opticalparametric oscillator (OPO) is used as a light source and combines a broad spectral cover-age and narrow bandwidth with a high output power and excellent mode characteristics.The performance of the technique is demonstrated by recording a rotationally cold spec-trum of the formyl cation, HCO+, in the CH stretching region. Absolute ion densities aredirectly derived [1].

Presently, experiments are prepared to record fully resolved spectra of ionic complexesof astrophysical relevance, with a focus on those species that may be considered reactiveintermediates in ion-molecule reactions in space [2]. Such complexes are generally relativelystrongly bound, and some experience measuring such species (e.g. Ar-N+

2 and N2-H+-N2

[3,4]) in direct absorption using special plasma techniques exists [5]. An extension tospecies such as (CO-CO)+ or H2-HCO+ is envisaged.

1. H. Verbraak, A.K.Y. Ngai, S.T. Persijn, F.J.M. Harren, H. Linnartz, Chem. Phys.Lett., 442 (2007) 145.2. W. Klemperer, Proc. Nat. Acad. Sci. U.S.A., 103, (2006) 12232.3. H. Verbraak, J.N.P. van Stralen, J. Bouwman, J.S. de Klerk, D. Verdes, H. Linnartz,F.M. Bickelhaupt, J. Chem. Phys., 123 (2005) 144305.4. D. Verdes, H. Linnartz, J.P. Maier, P. Botschwina, R. Oswald, P. Rosmus, P. Knowles,J. Chem. Phys., 111 (1999) 8400.5. H. Verbraak, D. Verdes, H. Linnartz, Int. J. Mass Spectrom., 267 (2007) 248.


CONTINUOUS-WAVE MID-INFRARED OPTICAL PARAMETRICOSCILLATOR WITH EXTENSIVE PUMP TUNING

MIKAEL SILTANEN, MARKKU VAINIO, AND LAURIHALONEN, Laboratory of Physical Chemistry, Department of Chem-istry, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University ofHelsinki, Finland.

Because of limited availability of suitable lasers in the mid-infrared region, methods basedon nonlinear optical effects such as frequency down-conversion in a nonlinear crystal areoften used. A common practical implementation of the effect is an optical parametricoscillator (OPO), where photons of a pump laser beam are annihilated to coherentlyproduce so-called signal and idler beam photons, which share the energy of the originalpump beam photon. Therefore, the idler beam is tunable by changing either pump orsignal beam wavelength. The OPO can be built so that the idler beam is in the mid-infrared and available for spectroscopic applications.1

High efficiency, high output power, and simplicity are achieved using a singly resonantconfiguration, where just one of the beams (typically signal) is resonating in the opticalcavity of the OPO. However, a singly resonant OPO requires high-quality pump laser. Thishas resulted in many practical constructions where coarse tuning is performed by changingthe signal beam wavelength through adjustments or tunable elements in the OPO cavity2,3

and narrow range scans are achieved by modulating the pump beam. While pump beammodulation may be fast, the adjustments in the optical cavity may require long time tostabilize and especially so if thermal issues are involved.4

We present a singly resonant, continuous-wave (cw) OPO that is tunable in a few secondsacross an extensive wavelength range with a high output power of up to 0.8 W in themid-infrared. Tuning is achieved by adjusting the pump beam wavelength. The OPOis pumped by a Ti:sapphire laser with up to 40 GHz mode-hop free scanning. Coarsetuning is possible within two regions of the mid-infrared spectrum: about 2.5 to 3.5 µmand 3.4 to 4.4 µm (roughly 4000 to 2860 cm−1and 2940 to 2270 cm−1). Single tuningregion is accessible by changing only the pump beam wavelength while the OPO cavityneeds no adjustments. The preferred region can be selected by choosing the poling periodof the nonlinear crystal in the OPO cavity. Both of the regions can be reached using thesame poling period by accepting narrower tuning ranges, in which case the preferred tuningregion depends on small adjustments to the OPO cavity. An etalon can be employed insidethe cavity for improved stability and scanning. The range and tuning rate of mode-hopfree scans are determined by the pump source.

1. M. Vainio, J. Peltola, S. Persijn, F. J. M. Harren, and L. Halonen, Opt. Express 16,11141 (2008).2. M. Vainio, M. Siltanen, J. Peltola, and L. Halonen, Opt. Express 17, 7702 (2009).3. M. Vainio, M. Siltanen, T. Hieta, and L. Halonen, Opt. Lett. 35, 1527 (2010).4. M. Vainio, J. Peltola, S. Persijn, F. J. M. Harren, and L. Halonen, Appl. Phys. B 94,411 (2009).


ULTRA HIGH RESOLUTION SPECTROSCOPY OF METHYLTRI-OXORHENIUM TOWARDS THE OBSERVATION OF PARITY NONCONSERVATION IN CHIRAL MOLECULES

C. STOEFFLER, B. DARQUIE, A. SHELKOVNIKOV, C.DAUSSY, O. LOPEZ, C. CHARDONNET and A. AMY-KLEIN,Laboratoire de physique des lasers, UMR7538, CNRS, Universite Paris13, Institut Galilee 99 avenue Jean-Baptiste Clement, 93430 Villeta-neuse, France Email: [email protected].

Since its theoretical prediction in 19741, parity non-conservation (PNC) in molecules hasnever been observed. Originating from the weak interaction, PNC should lead to frequencydifferences in the rovibrational spectrum of enantiomers of a chiral molecule. However theweakness of the effect represents a very difficult experimental challenge.A few years ago, a saturated absorption experiment in a Fabry Perot cavity was imple-mented to detect PNC effect on a transition of the C-F stretching band of CHFClBr at29.7 THz ( 990 cm−1). However the experimental fractional sensitivity of 10−13 (3 Hz)was insufficient to measure a frequency shift expected at 6 × 10−17 (1.7 mHz)2. We arenow aiming at setting up a new experiment based on 2-photon Ramsey spectroscopy ina supersonic beam3. This powerful ultra-high resolution spectroscopy technique has beendeveloped in our group with SF6

4. It should lead to a sensitivity of 10−15 for the fre-quency difference between left- and right-handed molecules. Moreover recent theoreticalwork5 indicates that the PNC shift would be 1000 times larger in some organometalliccomplexes and let us expect the first observation of molecular NCP.Chemist partners are currently trying to synthesize chiral derivatives of methyltrioxorhe-nium (MTO), a solid molecule at 300 K which sublimates at around 400 K3. We haveperformed high-resolution spectroscopy of MTO around its intense absorption band at975 cm−1, which is accessible with our ultra-stable spectrometer. We have obtained thefirst saturated absorption spectra in a cell at 300 K with a resolution as low as 50 kHz(2× 10−6 cm−1) (see Fig. 1). We have also developed a supersonic beam of MTO, usingHe as a carrier gas, and recorded linear absorption spectrum of this beam. This representsa first step towards ultra high resolution spectroscopy of chiral molecules in a beam.

Satu

rate

d ab

sorp

tion

ampl

itude

975.93580975.93570975.93560975.93550Wavenumbers (cm-1)

1. D. W. Rein, 1974, (J. Mol. Evol.), 4, 15.2. Ch. Daussy et al, 1999, (Phys. Rev. Lett.), 83, 1554.3. B. Darquie et al, to be published in Chirality.4. A. Shelkovnikov et al, 2004, (IEEE Quant. Electron.), 40, 1023.5. P. Schwerdtfeger et al, 2004, (J. Am. Chem. Soc.), 126, 1652.


FTMW STUDY OF THE CHIRALITY RECOGNITION BETWEENTWO DIFFERENT CHIRAL MOLECULES: THE GLYCIDOL-PROPYLENE OXIDE COMPLEX

JAVIX THOMAS, F. X. SUNA-HORI, NICOLE BORHO, YUNJIE XU , Department ofChemistry, University of Alberta, Edmonton, Canada T6G 2G2.

The chirality recognition effect in a prototype chiral molecular contact pair, i. e. theglycidol—propylene oxide complex, has been studied using rotational spectroscopy andhigh level ab initio calculations. Extensive ab initio calculations have been performed tolocate all possible low energy conformers of the diastereomeric pair and 14 minima havebeen found. The four most sable hetero and four homo chiral dimers, formed from the twolowest energy monomer conformations G+g- and G-g+ of the glycidol, were predicted to beclose in their stability. Jet-cooled rotational spectra of six of them have been detected usinga pulsed molecular beam Fourier transform microwave spectrometer and been assignedfor the first time. All the low energy binary conformers observed show one primaryintermolecular OH—O hydrogen bond and two secondary intermolecular CH—O hydrogenbonds. The effect of hydrogen bonding and van der Waals interactions on the relativestability of the chiral contact pairs will be discussed.

Presentation mode: posterComment: Session on chirality and chirality recognition

STUDY OF CHIRAL RECOGNITION IN THE PROTONATED SER-INE DIMER AND OCTAMER USING INFRARED MULTIPHOTONDISSOCIATION SPECTROSCOPY AND AB INITIO METHODS

FUMIE X. SUNAHORI, ELENA N. KITOVA, JOHN S.KLASSEN, AND YUNJIE XU, Department of Chemistry, Universityof Alberta, Edmonton, Canada T6G 2G2; GUOCHUN YANG, Depart-ment of Chemistry, Northeast Normal University, Changchun 130024,Jilin, P.R. China..

Previous mass spectrometry studies showed that serine can form magic-number proto-nated clusters such as serine octamer [Ser8 + H]+ and the protonated serine octamerexhibits strong preference for homochirality.a Although several candidate structures wereproposed, no conclusive conclusion could be drawn. We have recently combined a CWOPO laser in the 3000-4000 cm−1 regionwith a Fourier transform ion cyclotron (FRICR)mass spectrometer to perform infrared multiphoton dissociation (IRMPD) spectroscopicmeasurements. Using this technique, we have recorded IRMPD spectra of the proto-nated serine octamer and dimer. Both enatiopure and racemic samples have been usedin order to probe the infrared signatures for chiral recognition in these clusters and theirstructures. To aid the interpretation of the observed spectra, molecular structures andvibrational frequencies of the octamer and dimer have been predicted using DFT calcu-lations. Differences in chiral selectivity between the serine octamer and dimer will bediscussed.

aS. C. Nanita and R. G. Cooks Angew. Chem. Int. Ed. 45(554), 2006.

Presentation mode: posterTime required: MINITUES REQUIRED minComment: COMMENT TEXT

ROTATIONAL SPECTRUM OF GLYCINE AMIDE

ZBIGNIEW KISIEL, EWA BIA LKOWSKA-JAWORSKA, andLECH PSZCZO LKOWSKI, Institute of Physics, Polish Academy ofSciences, Al. Lotnikow 32/46, 02-668 Warszawa, Poland; JEAN-CLAUDE GUILLEMIN, Sciences Chimiques de Rennes, UMR 6226CNRS-ENSCR, Ecole Nationale Superieure de Chimie de Rennes, 35700Rennes, France.

Glycine amide, H2NCH2CONH2, may be considered as one of the possible precursorsof glycine in star forming regions. It can be formed by hydrolysis of another glycineprecursor, aminoacetonitrile, NH2CH2CN, and a second such step converts it to glycine.The rotational spectrum of glycine amide has not previously been studied and presently wereport the results of the first study of this spectrum, which has been taken to frequenciesof over 300 GHz.

The rotational spectrum of glycine amide is that of a rather asymmetric prolate molecule(κ = −0.68) and is dominated by a-type transitions. It proved to be a considerablechallenge for assignment since it is devoid of well defined characteristic line groupings. Inaddition the ground state is in the form of a strongly perturbed inversion doublet with anenergy level spacing of ca 10 cm−1. Nevertheless, once a sufficient number of broadbandspectral segments were recorded, successful assignment was reached with the use of theAABS package.a The assignment was confirmed by observation of the much weaker bR-and bQ-type transitions.

The rotational constants determined for glycine amide establish experimentally that itsgeometry is consistent with the global minimum geometry identified by quantum chemicalcalculations.b This geometry is similar to that found for aniline amidec and, in fact, also tothat of glycine II. There appears to be a stabilising intramolecular hydrogen bonding typeinteraction between the lone pair on the nitrogen in the amine group and the H–N bondin the amide group. Detailed information on the rotational spectrum of glycine amide anda discussion of the derived molecular properties are presented.

aZ. Kisiel et al. J. Mol. Spectrosc. 233, 231–243 (2005).bP.Li, Y.Bu, H.Ai, J. Phys. Chem. A 107 6419 (2003).cR.J.Lavrich, J.O.Farrar, M.J.Tubergen, J. Phys. Chem. A 103 4659 (1999).


TERAHERTZ SPECTROSCOPY OF ISOTOPIC SPECIES OF ACRY-LONITRILE

ADAM KRASNICKI, ZBIGNIEW KISIEL, Institute of Physics,Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warszawa,Poland; BRIAN J. DROUIN, JOHN C. PEARSON, Jet PropulsionLaboratory, California Institute of Technology, 4800 Oak Grove Drive,Pasadena, CA 91109-8099, USA.

Acrylonitrile (vinyl cyanide, CH2=CHCN) is an important molecule in star forming re-gions. A sizable dipole moment and a high abundance in the interstellar medium facilitateddetection even of its 13C species.a

The construction of more sensitive astronomical instruments covering frequencies into theTHz region, such as ALMA (Atacama Large Millimeter/Submillimeter Array) or the Her-schel Space Observatory, stimulated our effort to extend the laboratory data and to provideaccurate prediction in this frequency region for singly substituted isotopologues of acry-lonitrile. The rotational spectra of commercially available isotopologues: 13CH2=CHCN,CH2=CH13CN, CH2=CHC15N, and CH2=CDCN were obtained with harmonic multipli-cation techniquesb by recording several broad spectral segments at frequencies up to 1.2THz.

In this study we present a systematic analysis of the ground and the lowest vibrationallyexcited state v11 = 1 for four isotopologues. In the analysis we considered similar inter-actions between the ground state and v11 = 1 to those which were found in the parentspecies.c From the two-state fit we determined precise molecular constants for the twoanalysed states and their energy difference.

We also report assignment of ground state rotational transitions for six new doubly sub-stituted isotopic species of acrylonitrile. The availability of a larger set of rotationalconstants enabled determination of the complete rm and semi-experimental re moleculargeometries of acrylonitrile. The experimental results are discussed and compared withab initio calculations.

aH.S.P. Muller et. al, J. Mol. Spectrosc., 251 319-325 (2008).bB.J. Drouin et. al, Rev. Sci. Instrum., 76, 093113-1-10 (2005).cZ. Kisiel et. al, J. Mol. Spectrosc., 258, 26-34 (2009).


ISOMERICAL AND STRUCTURAL DETERMINATION OF N-HYDROXYUREA. MATRIX ISOLATION AND THEORETICALSTUDY

MAGDALENA SALDYKA, Faculty of Chemistry, University ofWroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland.

The structure, isomerization pathways and vibrational spectra of the biologically impor-tant N-hydroxyurea (HU) molecule were studied by matrix isolation FT-IR spectroscopyand molecular orbital calculations undertaken at the MP2/6-311++G(2d,2p) level of the-ory. In consonance with theoretical predictions, 1Ea represents the most stable ketoisomer in the gas phase, being the dominant species trapped in argon matrices, while the1Za isomer also contributes to the spectrum of isolated HU. According to the calculatedabundance values at the temperature of evaporation of the compound (393 K), the 1Eaand 1Za isomers together with a small contribution of 1Eb are expected to appear in theexperimental spectra. Since the barrier for interconversion 1Ea ←→ 1Eb is only about2 kJ mol−1, these two isomers are in equilibrium in the matrices and, at low tempera-ture, the population of the less stable 1Eb form is too small to enable its observation.Full assignment of the observed spectra of N-hydroxyurea was undertaken on the basisof comparison with theoretical data. The C-PCM calculations performed for the HU iso-mers in water solution revealed that 1Ea remains the lowest energy structure and theorder of stability of the isomers changes in water with respect to the gas phase as follows:1Ea>1Eb>1Zb>1Za.


IDENTIFICATION OF THE C7 AND C5 PEPTIDE CONFORMA-TIONS IN ALANINE AND PROLINE DERIVATIVES

G. BALLANO, ANA I. JIMENEZ, CARLOS CATIVIELA, De-partamento de Quimica Organica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza (Spain); CARLOS CABEZAS, SANTI-AGO MATA, MARCELINO VARELA, M. ANGELES LO-ZOYA, JUAN C. LOPEZ, JOSE L. ALONSO, Departamento deQuimica Fisica y Quimica Inorganica, Facultad de Ciencias, Universi-dad de Valladolid, E-47005, Valladolid, Spain.

Rotational spectra of the smallest peptide systems derived from alanine (Ala) and proline(Pro), namely the amino acids blocked at the N- and C-termini with amide groups (RCO-Ala-NHR’, RCO-Pro-NHR’; R = Me, R’ = Me or H), have been examined with laserablation molecular beam Fourier transform microwave (LA-MB-FTMW) spectroscopy.1

The experimental rotational and 14N nuclear quadrupole coupling constants have beencompared to ab initio theoretical predictions. The C7 and C5 peptide conformations (in-tramolecularly hydrogen-bonded seven- or five-membered cycle, respectively) have beenunequivocally identified in the supersonic expansion. The ability to identify peptide con-formations suggest that it soon may be possible to explore the structures of larger peptidesusing LA-MB-FTMW spectroscopy.

1. J. L. Alonso, C. Perez, M. E. Sanz, J. C. Lopez, S. Blanco, Phys. Chem. Chem. Phys.11, 617-627 (2009)


INFRARED SPECTROSCOPY OF SMALL DIAMONDOIDS. ANALY-SIS OF THE HIGH RESOLUTION SPECTRUM OF ADAMANTANEC10H16

O. PIRALI, D. Balcon, M. Vervloet, Ligne AILES – SynchrotronSOLEIL, L’Orme des Merisiers, F-91192 Gif-sur-Yvette, France; V.BOUDON, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR5209 CNRS-Universite de Bourgogne, 9. Av. A. Savary, BP 47870,F-21078 Dijon Cedex, France; J. OOMENS, Inst. Plasma Phys. Rijn-huizen, FOM, NL-3439 MN Nieuwegein, Netherlands.

The unambiguous presence of presolar diamond nanocrystals in meteorites led several as-trophysical groups to look for the signature of this family of molecules in the interstellarmedium; mostly comparing IR observations with low resolution laboratory resultsab. Wewill present the IR and FIR spectra of gas phase adamantane C10H16 and diamantaneC14H20 recorded using the Bruker IFS 125 coupled to a multipass cell (absorption pathlength of 150 m) of the AILES beamline at SOLEIL. In particular we obtained the IR spec-trum of gas phase adamantane in the 300–3000 cm−1 spectral region with an unapodizedresolution of about 0.001 cm−1. While the most intense 3 µm bands appear as unresolvedbroad feautures, seven fundamental bands show rotationally resolved structures typical ofTd spherical tops. The analysis of all the resolved bands has been performed thanks tothe XTDS and SPVIEW softwares developed in Dijon for such moleculesc. In our prelim-inary analysis, each band can be considered as isolated and we get very good fits of linepositions, with a root mean square deviation better than 5× 10−4 cm−1 for J values upto 100 or more in each case. The resulting synthetic spectra will permit an active searchof this very stable specie in different sources of the interstellar medium.

aOomens J, Polfer N , Pirali O, Ueno Y, Maboudian R , May PW, Filik J, Dahl JE, Liu SG,Carlson RMK, J. Mol. Spec. , 238, 158–167 (2006)

bPirali O, Vervloet M, Dahl JE, Carlson RMK, Tielens AGGM, Oomens J, Ap. J. , 661, 919–925(2007)

cCh. Wenger, V. Boudon, M. Rotger, M. Sanzharov and J.-P. Champion, J. Mol. Spectrosc.,251 102–113 (2008).

Presentation mode: posterTime required: MINUTES REQUIRED minComment: COMMENT TEXT

APPROXIMATE THEORETICAL MODEL FOR THE FIVE ELEC-TRONIC STATES ARISING FROM THE 3d9 CONFIGURATION INNICKEL HALIDES AND FOR ROTATIONAL LEVELS OF THE Ω =1/2 STATES

JON T. HOUGEN, Optical Technology Division, National Institute ofStandards and Technology, Gaithersburg, MD 20899-8441, USA.

This poster is divided into two parts. In the first part an effective Hamiltonian for anon-rotating diatomic molecule containing only crystal-field and spin-orbit operators isset up to describe the energies of the five spin-orbit components that arise in the groundelectronic configuration of the nickel monohalides. The model assumes that bonding inthe nickel halides has the approximate form Ni+X−, with an electronic 3d9 configurationplus closed shells on the Ni+ moiety and a closed shell configuration on the X− moiety.From a crystal-field point of view, interactions of the positive d-hole with the cylindricallysymmetrical electric charge distribution of the hypothetical NiX− closed-shell core canthen be parameterized by three terms in a traditional expansion in spherical harmonics:C0 + C2Y20(θ, φ) + C4Y40(θ, φ). Interaction of the hole with the magnetic field generatedby its own orbital motion can be parameterized by a traditional spin-orbit interactionoperator AL.S. The Hamiltonian matrix is set up in a basis set consisting of the tenHund’s case (a) basis functions |Λ,Σ > that arise when L = 2 and S = 1/2. A least-squares fit of the five lowest observed electronic spin-orbit component states in NiF andNiCl was then carried out in terms of the four parameters C0, C2, C4, A which led to goodagreement except for the two |Ω| = 1/2 states. The large equal and opposite residuals ofthe |Ω| = 1/2 states could be reduced to those for the |Ω| = 3/2 and |Ω| = 5/2 states byfixing A to its value in Ni+ and then introducing an empirical correction factor for oneoff-diagonal spin-orbit matrix element. In the second part of the paper the usual effectiveHamiltonian B(J-L-S)2 for a rotating diatomic molecule is used to derive expressions forthe Ω-type doubling parameter p in the two |Ω| = 1/2 states. These expressions show (forcertain sign conventions) that the sum of the two p values should be 2B, but that theirdifference can be as large as 10B. These theoretical results are in good agreement withthe two observed p values in NiF and with the one p value observed in NiCl. The presentformalism should also be directly applicable to NiBr and NiI.


HIGHLY EXCITED 1Πu ELECTRONIC STATES IN 7Li2

W. JASTRZEBSKI, Institute of Physics, Polish Academy of Sciences,Al. Lotnikow 32/46, 02-668 Warsaw, Poland; A. GROCHOLA, P.KOWALCZYK, Institute of Experimental Physics, University of War-saw, ul. Hoza 69, 00-681 Warsaw, Poland.

In the present experiment we used the polarization labelling spectroscopy techniqueto characterize three previously unknown highly excited 1Πu electronic states in 7Li2molecule. The easiest way to reach highly excited electronic states experimentally isstepwise excitation via some intermediate, low lying level, because two visible photonscan be used then. When we start from a ground molecular state of 1Σ+

g symmetry, theselection rules allow in this case excitation of 1Λg states with Λ = Σ, Π, ∆. Transitionsto states of ungerade symmetry require an odd number of photons. This can be realizedby one photon absorption, conceptually simple but experimentally less convenient since aUV or VUV radiation is needed. In the current experiment we used an optical parametricoscillator/amplifier system provided with a frequency doubler (Continuum, Sunlite EX,pumped with an injection seeded Nd:YAG laser, Powerlite 8000). The system deliveredUV pulses of 3mJ energy, 10ns duration and a spectral width below 0.16 cm−1 tuneablefor purposes of the present experiment between 37300 and 40900 cm−1. In this range wehave observed and identified 3 states of 1Πu symmetry and we have determined salientmolecular constants (Dunham coefficients) for these states. We have found that togetherwith the 41Πu and 61Πu states known from previous experiments1,2,3 they apparently forma Rydberg series corresponding to excitation of the npπu electron. The negative value ofthe quantum defect for the series suggests interaction with the low lying valence C1Πu

state4 correlated to doubly excited atomic configuration 2p+2p.

1. Z. Jedrzejewski-Szmek, A. Grochola, W. Jastrzebski, P. Kowalczyk, Chem. Phys.Lett. 444, 229 (2007).2. Z. Jedrzejewski-Szmek, A. Grochola, W. Jastrzebski, P. Kowalczyk, Opt. Appl. inprint(2010).3. A. Grochola, W. Jastrzebski, P. Kowalczyk, Mol. Phys. 106, 1375 (2008).4. M K. Kubkowska , A. Grochola, W. Jastrzebski, P. Kowalczyk, Chem. Phys. 333, 214(2007).

Presentation mode: posterComment: None

THE b3Π(Ω = 1) STATE OF NaCs STUDIED BY POLARISATION LA-BELLING SPECTROSCOPY

ANNA GROCHOLA, PAWE L KOWALCZYK, Institute of Exper-imental Physics, University of Warsaw, ul. Hoza 69, 00-681 Warsaw,Poland; W LODZIMIERZ JASTRZEBSKI, Institute of Physics, Pol-ish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland.

For a number of years we have been using the polarisation labelling spectroscopy (PLS)method to study excited electronic states of diatomic alkali metal molecules accessible inone photon transitions from the molecular ground states. Our variant of the PLS methoda

is based on a V-type optical-optical double resonance excitation scheme employing twoindependent laser sources. This technique elegantly surmounts the difficulty of resolvingand analyzing highly congested molecular spectra. With a proper choice of frequencies andpolarisation of two laser beams, interacting with a given molecular sample, only transitionsfrom a few known rovibrational levels in the ground state are observed, resulting in spectrawith easily resolved and understandable rotational structure. Although the polarisationspectra are Doppler-limited but the precision in determination of molecular constants andpotential energy curves (PECs) from such experiments is adequate to majority of needsand fully sufficient for comparison with modern ab initio calculations.In this contribution we present experimental characterisation of the b3Π1 state in NaCs.The state is observed via the nominally forbidden b3Π1 ← X1Σ+ band system, detectablebecause of a transition from Hund’s case (a) to case (c) in the relatively heavy NaCsmolecule. A wide range of rovibrational levels 0 < v < 68, 13 < J < 51 is observed.By using the inverted perturbation approach (IPA) to our experimental data we havesuccessfully obtained a rotationless PEC of the b3Π1 state which reproduces the energylevels with a standard deviation of 0.11 cm−1 for 99.7 % of the potential well depth.The resulting potential is of importance for understanding of photoassociation spectra ofNaCsb.

asee e.g. A. Grochola, W. Jastrzebski, P. Kortyka, and P. Kowalczyk, J. Mol.Spectrosc. 221, 279 – 284 (2003) and references therein.

bC. Heimberger, J. Kleinert, P. Zabawa, A. Wakim, and N. P. Bigelow, New J. Phys.11, 055042 (2009).

Presentation mode: posterTime required: – minComment: –

UV FOURIER TRANSFORM ABSORPTION SPECTROSCOPY OFTHE A1Σ+

u - X1Σ+g SYSTEM OF Mg2

HORST KNOCKEL, S. RUHMANN, E. TIEMANN, Centre forQuantum Engineering and Space-Time Research (QUEST) and Institutefor Quantum Optics, Universitat Hannover, Welfengarten 1, D-30167Hannover.

Alkaline earth atoms like Mg, Ca and Sr are presently under consideration for devel-opment of optical clock standards, as they provide narrow optical transitions promisingmuch higher frequency stability and accuracy than is expected for the present Cs-basedmicrowave clocks. To reach the ultimate accuracy aimed at, e.g. the cold collision proper-ties of the corresponding atoms must be known. Thus precise knowledge of the molecularpotential energy curves (PEC) is necessary, covering the whole range of the well and thelong range close to the asymptotes.While for Ca2

a,b and for Sr2c,d the X1Σ+

g ground states have been characterized up tothe asymptote, the information for Mg is less completee,f,g. Mg2 is special in that thespectrum is in the near UV range, where tunable lasers are not easily available. Lackingsuch lasers for excitation of the A - X spectrum of Mg2, we applied conventional absorp-tion spectroscopy with a UV Fourier transform spectrometer (FTS). The light from aDeuterium lamp was directed through a Mg/Mg2 heat pipe into the input aperture of theFTS. The observed dense spectrum is analyzed employing a specific computer program forsimulation and fitting of parts of the spectrum to account for the severe overlap of linesdue to the abundances of various isotopologues.The accuracy of the line frequencies is improved by about a factor of four compared toprevious worke,f,g due to better spectral resolution, and the consistence of the modeldescription is improved by directly fitted PECs for both states involved. Various pertur-bations in the upper state have been identified, which were not known before.The status of the investigation will be reported.

aO. Allard et al., Eur. Phys. J. D 35, 483 (2005)bO. Allard et al., Eur. Phys. J. D 26, 155 (2003)cA. Stein et al., Eur. Phys. J. D 57, 171 (2010)dA. Stein et al., Phys. Rev. A 78, 042508 (2008)eW.J. Balfour. A.E. Douglas, Can. J. Phys. 48, 901 (1970)fH. Scheingraber, C.R. Vidal, J. Mol. Spec. 68, 46 (1977)gC.R. Vidal, H. Scheingraber, J. Chem. Phys. 66, 3694 (1977)


THE EMISSION SPECTRUM OF THE A2∆–X2Π BAND SYSTEM OFCD RADICAL

MIROS LAW ZACHWIEJA, RYSZARD KEPA, RAFA LHAKALLA, and WOJCIECH SZAJNA, Atomic and Molecu-lar Physics Laboratory, Institute of Physics, University of Rzeszow,Rzeszow, Poland.

The visible spectrum of CD has been investigated at high resolution between 22 900 and24 000 cm−1 using conventional spectroscopic technique. The CD radicals were generatedby a dc discharge in a CD4 and He mixture in a hollow-cathode lamp with two anodes. Theemission from the discharge was observed with a plane grating spectrograph and recordedby translating on a linear stage an exit slit and photomultiplier tube (HAMAMATSUR943-02) along the focal curve of the spectrograph. The line intensities were measured bya single photon counting, and positions of the exit slit were measured using He–Ne laserinterferometer synchronized with the photon counting board. The total number of themeasurement points was about 73 000, for one 215-mm long scan with the sample stepof 3 µm. Simultaneously recorded Th lines1, obtained from several overlapped orders ofthe spectrum from a hollow-cathode tube were used for absolute wavenumber calibration.The 0–0, 1–1, 2–2 and 3–3 bands of the A2∆–X2Π transition have been identified androtationally analyzed. The new data (about 1200 lines, 12 branches with Jmax = 36.5,f = 270, σ = 0.003 cm−1 for strongest 0–0 band) were elaborate with help of X2Π stateparameters – reported by Morino et al.2 or scaled from the CH constants.3 The final calcu-lations of the positions of the molecular linecenters were supported by (from preliminarymeasurements) an earlier set of sorted wavenumbers of the CD and CH lines in measuredregion (about 1500 lines). The reduction of the spectrum for the individual bands has beenperformed via a nonlinear least-squares fit with the effective Hamiltonians of Brown et al.4

The merged molecular parameters for the observed levels and the equilibrium molecularconstants were compared with calculations performed within the Born–Oppenheimer ap-proximation and a small disagreement for some of them has been found, due to partialbreakdown of the Born–Oppenheimer approximation. The electronic isotopic shift andthe Λ-doubling constants in the A2∆ state were obtained for the first time.

1. B. A. Palmer and R. Engleman, Jr.,”Atlas of the Thorium Spectrum,” Los AlamosNational Laboratory, Los Alamos, NM, unpublished.2. I. Morino, K. Matsumura and K. Kawaguchi, J. Mol. Spectrosc. 174, 123–131 (1995).3. M. Zachwieja, J. Mol. Spectrosc. 170, 285–309 (1995).4. J. M. Brown, E. A. Colbourn, J. K. G. Watson, and F. D. Wayne, J. Mol. Spectrosc.74, 294–318 (1979).


NUCLEAR QUADRUPOLE COUPLING IN HAFNIUM CHALCOGENIDES

DAVID A. DEWALD, JENS-UWE GRABOW, Gottfried Wilhelm Leibniz

Universität Hannover, Institut für Physikalische Chemie, Callinstraβe 3A,

30167 Hannover, Germany.

Fourier-Transform Microwave Spectroscopy (FTMW) meets the quantitative

prepositions to allow for accurate determination of tiny effects in the qualities of the

examined molecules. Within the scope of this analysis the spectra of the hafnium

chalcogenides hafnium oxide and hafnium sulfide obtained by using FTMW have been

investigated. Since 177

Hf and 179

Hf nuclei both possess a nuclear spin larger than 1,

which is a precondition to a nuclear quadrupole moment, the interaction of the

quadrupole moment with the electric field gradient (EFG) gives rise to the quadrupole

interaction. After removal of vibrational and centrifugal distortion effects, the

magnitude of this interaction should be directly proportional to quadrupole moments of

the isotopes. However, as reported by Koch et al.a there is another effect in the

quadrupole interaction visible in the rotational spectra: The quadrupole shift based on

the assumption of a finite nuclear volume and its penetration by the surrounding

electrons. Up to now there was no experimental proof to this effect, because a

determination requires very high precision measurements. Since the Quadrupole Shift is

estimated to be large for heavy nuclei, the hafnium chalcogenides studied in our

experiments together with their substantial nuclear quadrupole moments and thus huge

coupling constants (NQCC) are most suitable to the determination of the effect. Indeed,

according to the theoretical predictions there has been found an effect which can be

described as Quadrupole Shift.

aKatrin Koch, Klaus Koepernik, Dimitri Van Neck, Helge Rosner, and Stefaan

Cottenier, Phys. Rev. A. 81, 032507 (2010)

TIME-RESOLVED FTIR EMISSION SPECTROSCOPY OF Cu, AgAND Au IN THE 1300–4000 cm−1 REGION: TRANSITIONS INVOLV-ING f AND g STATES AND OSCILLATOR STRENGTHS

S. CIVIS, ; I. MATULKOVA, ; J. CIHELKA, ; P. KUBELIK,; V. E. CHERNOV, J. Heyrovsky Institute of Physical Chemistry,Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague8, Czech Republic.

We report on a study of the emission spectra of Cu, Ag and Au vapors in a vacuum (10−2

Torr) formed in ablation of an the metal targets by a high-repetition rate (1.0 kHz) pulsednanosecond ArF laser (λ = 193 nm, output energy of 15 mJ). The time-resolved infraredemission spectra of Cu, Ag and Au was recorded in the 1300–4000 cm−1 spectral regionusing the Fourier transform infrared spectroscopy technique with a resolution of 0.02 cm−1.The time profiles of the measured lines have maxima at 5–6 µs after a laser shot and displaynon-exponential decay with a decay time of 3–7 µs. We report 46 lines not previouslyobserved and revise energy values for 38 levels of which 11 was not reported previously;these data are given with an uncertainty of 0.0005–0.016 cm−1. The line classificationis performed using relative line strengths expressed in terms of transition dipole matrixelements calculated with the help of the Fues model potential; these calculations showagreement with the large experimental and calculated data sets available in the literature.In addition to these data we also calculate transition probabilities, line and oscillatorstrengths for a number of transitions in 1300–5000 cm−1 range between closed-shell-corestates of Cu, Ag and Au.

Presentation mode: not specified

ABSORPTION AND LUMINESCENCE EXCITATION SPECTRA OFClF IN THE VAC UV REGION

VADIM A. ALEKSEEV, Institute of Physics, St.Petersburg StateUniversity, Uljanovskaja St.1, Peterhof, 198504 Russia; NIKOLAUSSCHWENTNER, Institut fur Experimentalphysik, Freie UniversitatBerlin, Arnimallee 14, D-14195, Germany.

Absorption and luminescence excitation spectra of ClF are recorded in the vacuum ultra-violet employing synchrotron radiation. A broad band (120-130 nm) due to transition tothe ion-pair state E(0+) and sparse transitions to Rydberg states are observed. All Ryd-berg states are predissociated and their excitation yields no luminescence. Perturbationsby the 4sσ1Π1 and 4pπ1Σ+ Rydberg states result in characteristic dips in the E(0+) stateluminescence excitation spectrum. Excitation above the Cl* + F dissociation thresholdresults in luminescence from ion-pair states of ClF or Cl2 populated in reaction of Cl*with ClF or Cl2We are grateful to the BESSY staff and especially to Dr. Reichardt. VA acknowledgesfinancial support from the Deutsche Forschungsgemeinschaft.


DIODE LASER SPECTROSCOPY OF THE SECOND OVERTONEBAND OF HYDROGEN IODIDE

B. L. BRINICH, J. D. HACKLEY, J. L. HARDWICK,M. K. HUMPHREY, Z. R. JONES, J. LARA,N. R. LINDQUIST, D. P. MEYERS, M. J. MILLER, B. V. SIL-VER, AND M. R. WETHERELL, Department of Chemistry,University of Oregon, Eugene, OR 97401, USA.

High resolution diode laser spectroscopy has been used to measure the (3,0) band ofhydrogen iodide at 1529 nm. Both direct absorption spectra and wavelength modulationspectra have been observed. An examination of the line shapes of the P(2), P(1), R(0),and R(1) transitions shows clear evidence of hyperfine splitting due to iodine nuclearquadrupole coupling, as has been reported by Matsushima et al.a

On inspection, the shapes of higher-J lines are also distorted by quadrupole coupling,though less information can be extracted from them. Combining these results with thoseof Chance et al.b allows an improved determination of the line positions and excited stateterm values.

Figure 1. The derivative of the R(1) line of the 3-0 band of HI. The x axis is in cm−1,and the y axis is arbitrary.

aFusakazu Matsushima, Shinya Kakihata, and Kojiro Takagi, J. Chem. Phys. 94, 2408-12 (1991)bKelly V. Chance, Thomas D. Varberg, Kwangjai Park, and Lyndon R. Zink, J. Mol. Spectrosc

162, 120-126 (1993)


BENCHMARKING QUANTUM CHEMISTRY WITH ROTATIONALSPECTROSCOPY OR BENCHMARKING ROTATIONAL SPEC-TROSCOPY WITH QUANTUM CHEMISTRY?

CRISTINA PUZZARINI, Dipartimento di Chimica ”G. Ciami-cian”, Universita di Bologna, Via Selmi 2, I-40126 Bologna, Italy;JURGEN GAUSS, Institut fur Physikalische Chemie, UniversitatMainz, D-55099 Mainz, Germany.

Quantum chemistry has nowadays reached such an advanced level that highly accurateresults can be achieved for energies and properties of small to medium-sized molecules.For these high-level calculations the requirements are efficient treatment of electron cor-relation via coupled-cluster theory, basis-set extrapolation techniques, incorporation ofcore correlation, relativistic as well as vibrational effects together with the use of suitableadditivity schemes.Nevertheless, despite all the progress made so far, it is still essential to benchmark theresults from quantum-chemical calculations. Data from rotational spectroscopy are ideallysuited for this purpose, as this technique provides, in particular for small molecules inthe gas phase, highly accurate results. On the other hand, however, measurements andanalyses of rotational spectra are not often straightforward. State-of-the-art quantum-chemical computations are therefore needed to guide the investigation and in particular toassist in the determination of the spectroscopic parameters of interest. Quantum chemistryin this way allows to verify (“benchmark”) results from rotational spectroscopy.A statistical analysis of the accuracy of theoretically predicted rotational constants willbe presented as an example for the benchmark of quantum chemistry via rotationalspectroscopy1. On the other hand, the determination of the hyperfine parameters ofdihalogencarbenes (CF2 and CCl2) will show the need of “benchmarking” results fromexperiments2.Based on all the considerations given above, the answer to the “title question” turns outto be not clear-cut. What we suggest instead is to exploit a fruitful interplay of theory(quantum chemistry) and experiment (rotational spectroscopy). The power of such aninterplay will be demonstrated by a few examples. In particular, the determination of anabsolute 17O NMR scale via the analysis of the rotational spectrum of H2

17O (Ref. 3) andthe evaluation of equilibrium structures of substituted diacetylenes via the correspondingrotational constants4 will be presented.

1. C. Puzzarini, M. Heckert, and J. Gauss, J. Chem. Phys., 128, 194108 (2008).2. C. Puzzarini, S. Coriani, A. Rizzo, and J. Gauss, Chem. Phys. Lett., 409, 118 (2005).3. C. Puzzarini, G. Cazzoli, M. E. Harding, J. Vazquez, and J. Gauss, J. Chem. Phys.,131, 234304 (2009).4. S. Thorwirth, M. E. Harding, D. Muders, and J. Gauss, J. Mol. Spectrosc., 251, 220(2008); P. Botschwina and C. Puzzarini, J. Mol. Spectrosc., 208, 292 (2001); G. Cazzoli,L. Cludi, M. Contento, and C. Puzzarini, J. Mol. Spectrosc., 251, 229 (2008).


A LOW TEMPERATURE ABSORPTION SPECTRUM OF LaF3

FROM FIRST PRINCIPLES

SERGEI N. YURCHENKO, Physikalische Chemie, TU Dresden, D-01062 Dresden, Germany; VICTOR G. SOLOMONIK, ALEXAN-DER N. SMIRNOV, and OLEG A. VASILIEV, Ivanovo State Uni-versity of Chemistry and Technology, Engels St. 7, Ivanovo 153000,Russia; ANDREY YACHMENEV, Max-Planck-Institut fur Kohlen-forschung, Kaiser-Wilhelm-Platz 1, D–45470 Mulheim an der Ruhr,Germany.

We report new ab initio potential energy and dipole moment surfaces of a near-planar pyra-midal molecule LaF3. The potential energy surface was calculated at the coupled clusterCCSD(T) level of theory using the TZ, QZ, and 5Z quality basis sets with a subsequentextrapolation to the complete basis set limit. For the dipole moments surface of LaF3

the CCSD/QZ level of theory was employed. With these new surfaces, we have carriedout calculations of rovibrational energies for LaF3, and we have simulated the gas-phaseLaF3 absorption spectrum at low temperature T = 5 − 20 K in the wavenumber range0-2000 cm−1 employing the variational method TROVE. The simulated spectrum is com-pared to experimental infrared spectrum of the lanthanum trifluoride molecule trapped insolid N2, Ar, and Ne matricesa. The fundamental bands representing the stretching andasymmetric bending modes of the free molecule are found to be in good agrement withthe experimental data for the Ne matrix-isolated LaF3. However the computed inversion(‘umbrella’) bands of the free molecule deviate substantially from their experimental IRmatrix-isolation counterparts. The electronic structure calculations show that the inver-sion barrier of a free LaF3 molecule, 121 cm−1, can change significantly if the moleculeis trapped in a matrix. We investigate how a variation of the barrier and the associatedchange of the equilibrium geometry affect the absorption spectrum of LaF3. The matrixeffects on the LaF3 structural and spectroscopic properties are discussed.

V.G.S., A.N.S., and O.A.V. acknowledge support from the Russian Foundation for BasicResearch (Grant No. 09-03-01032).

aJ. W. Hastie, R. H. Hauge, and J. L. Margrave, J. Less-Common Met. 39, 309 (1975)

Presentation mode: posterTime required: 15 min

INFRARED AND RAMAN SPECTRA OF MnF3: AN AB INITIOSTUDY

VICTOR G. SOLOMONIK and ANDREW A. MUKHANOV,Ivanovo State University of Chemistry and Technology, Engels St. 7,Ivanovo 153000, Russia.

The MnF3 (T-shape C2v) molecule vibrational spectra are studied ab initio. To com-pute the force field and vibrational frequencies the CCSD(T) level of theory is appliedwith a series of Douglas-Kroll relativistic correlation consistent weighted core-valence ba-sis sets cc-pwCVnZ-DK (Mn), aug-cc-pVnZ-DK (F), n= T, Q, 5, and with subsequentextrapolation to the complete basis set limit. The infrared intensities are computed atthe ACPF/5Z, and Raman activities – at the MP2/TZ level of theory. The predictedspectra are compared with the MnF3 matrix isolation IR and Raman spectroscopy dataa.The theory suggests a plausible interpretation of both high (Mn–F stretching) an low-frequency (bond bending and out-of-plane bending) regions of the observed spectra. Anobservation of only one feature in a low-frequency range of IR and Raman spectra (185cm−1 in Ne, 182 cm−1 in Ar) is explained by an accidental near-degeneracy of the in-planebond bending ν3(a1) and out-of-plane bending ν6(b1) frequencies (188.2 and 189.0 cm−1

– CCSD(T)/CBS). The only ν3 was observed in the Raman spectrum (since ν6 exhibitsa very low Raman activity), and both ν3 and ν6 (overlapped) – in the IR spectrum. Thethird MnF3 bending frequency – ν5(b2) = 175 cm−1 (CCSD(T)/CBS) – was not detectedin the spectroscopic experiment due to its low IR and Raman intensity.

The authors gratefully acknowledge support from the Russian Foundation for Basic Re-search (Grant No. 09-03-01032).

aV. N. Bukhmarina and Yu. B. Predtechenskii, Optika i spectroscopia 80, 762 (1996)

Presentation mode: posterTime required: 15 min

GLOBAL RO-VIBRATIONAL ANALYSIS OF HYDROGEN SELENIDE(H2

80Se) BASED ON ANHARMONIC OPERATORS.

O. ALVAREZ-BAJO, M. CARVAJAL, F. PEREZ-BERNAL, Depar-tamento de Fısica Aplicada, Facultad de Ciencias Experimentales, Universidadde Huelva, 21071 Huelva, Spain; R. LEMUS, Instituto de Ciencias Nucle-ares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543,04510 Mexico, DF, Mexico.

The ro-vibrational spectrum of Hydrogen Selenide (H280Se) in its ground electronic state is

presented. The quantum mechanical ro-vibrational kinetic energy an potential energy function isconsidered as a Taylor expansion in internal coordinates of Morse local oscillators. Thereafter,the local Morse coordinates, and momenta, are expanded in terms of the Morse Potential laddersoperators. Only polyad-conserving terms are considered. Expansions of the kinetic and potentialenergies of the ro-vibrational Hamiltonian are considered up to sextic terms. The resultingHamiltonian was diagonalized using a symmetry-adapted basis, generated by the eigenfunctionmethod ab, from the direct product between of the full vibrational and rotational basis. A globalenergy fit is carried out for 1439 experimental energies up to 8000 cm−1 (Max. Polyad =6,Jmax =10) obtaining a rms deviation of 0.75 cm−1.

This work is supported by Andalusian Government (Spain) under proyect P07-FQM-03014 andCONACyT, Mexico.

aJ.Q.CHEN, Group Representation Theory for Physicists,World Scientific, 1989.bR. LEMUS, 2003 Mol.Phys., 101 2511-2528.


ROVIBRATIONAL STATES OF THE KRATZER OSCILLATOR INTHE QUANTUM PHASE SPACE REPRESENTATION

J. STANEK, Faculty of Chemistry, Adam Mickiewicz University, PL-60-780 Poznan, Poland.

The Wigner quasi-probability distribution introduced by Eugene Wigner1 in 1932 to studyquantum corrections to classical statistical mechanics is a special type of probability dis-tribution. Although it plays a role analogous to that of classical probability distribution,it could be treated only as a quasi-probability distribution, because it is not positive ev-erywhere in the phase space. Despite this drawback, it has been used with success in manyareas of quantum mechanics providing an alternative framework in which the quantumproblems can be treated in terms of classical concepts. However, we can refer only to a fewsimple quantum system for which the rigorous solutions of the Wigner function are known.One of the reasons for the lack of the explicit expression for the Wigner function is thepresence of the centrifugal term in the corresponding Schroedinger equation. Fortunately,in our case, we can use a very simple mathematical trick that maps the rotating Kratzeroscillator onto the one-dimensional Morse oscillator. This map is know in literature asLagner2 transformation, and was first applied to the rotating Kratzer oscillator in Cooper3

paper. The main advantage of this transformation is that a two-dimensional problem canbe reduced to a one-dimensional with redefined parameters for the Morse oscillator forwhich the Wigner function is well-known4. Using this transformation, we can calculatethe Wigner function of the rotating Kratzer oscillator for arbitrary quantum number nand J .

1. E. P. Wigner, Phys. Rev. 40, 749 (1932).2. R. E. Langer, Phys. Rev. 51, 669 (1937).3. I. L. Cooper, Int. J. Quant. Chem. 49, 25 (1994).4. G. W. Bund and M. C. Tijero, J. Phys. A 37, 3687 (2004).

Presentation mode: posterTime required: 15 minComment: The Wigner function of the rotating Kratzer oscillator

NONADIABATIC POTENTIAL FOR THE HYDROGEN MOLECULEIN GROUND ELECTRONIC STATE

MATTI SELG, Institute of Physics of the University of Tartu, Riia142, 51014 Tartu, ESTONIA.

Nonadiabatic corrections to a potential energy surface (PES) of a diatomic molecule can beascribed to coordinate-dependent corrections to the nuclear reduced mass. Recently, theseR-dependent corrections to both vibrational (W‖) and rotational (W⊥) inverse masseshave been explicitly calculated for the H2 molecule 1,2. As a result, one gets a modifiedSchrodinger equation

Φ′′vJ(R) =VvJ(R)− EvJ

CΦvJ(R) (C ≡ h2

2m)

for the nonadiabatically corrected effective PES

VvJ(R) = V (R) + δV (R) +C +W⊥(R)−W‖(R)

R2J(J + 1) +

EvJC

W‖(R),

which depends on both vibrational (v) and rotational (J) quantum numbers. Here V (R) isthe Born-Oppenheimer potential, δV (R) includes all state-independent (adiabatic, nona-diabatic, etc.) corrections, and the transformed radial eigenfunction ΦvJ(R) is normalizedby the condition

∫[ΦvJ(R)]2 exp

(−W‖(R)

C

)dR = 1.

The effective PES contains an additional correction term EvJC W‖(R) specific to any

particular rovibrational state. Let us denote δEvJ = EvJ − E0vJ , where E0

vJ is theknown approximate energy eigenvalue. Since both W‖(R) and δEvJ are small quanti-ties ( δEvJC W‖(R) ∼ 10−4 ÷ 10−3 cm−1 for the ground state H2 molecule 3), it practicallymakes no difference if one uses E0

vJ instead of EvJ in calculations. Thus, although VvJ(R)is state-dependent, all its constituents except δV (R) can be considered to be known. As-suming that the real eigenvalues EvJ have been ascertained experimentally with sufficientaccuracy, one therefore can apply an appropriate inverse perturbational scheme to deter-mine δV (R). Such an approach will be described and illustrated in this presentation.

1. K.L. Bak, S.P.A. Sauer, J. Oddershede, J.F. Ogilvie, Phys. Chem. Chem. Phys. 7,1747 (2005).2. K. Pachucki, J. Komasa, J. Chem. Phys. 130, 164113 (2009).3. M. Selg, Mol. Phys. 108, 687 (2010).


60-GHZ OXYGEN BAND: TO THE EXTENSION OF THE MIXINGMODEL

D.S. MAKAROV, M.Yu. TRETYAKOV, IAP RAS, Uljanova str.46, 603095, Nijniy Novgorod, Russia; P.W. ROSENKRANZ, Mas-sachusetts Institute of Technology, Cambridge, MA 02139,

USA.

In the millimeter-wave range, widely used for atmospheric applications, wireless commu-nications, remote sensing etc., molecular oxygen has a strong band between 50 and 70GHz and a single spectral line at 118.75 GHz. Both the band and the line are formedby fine-structure magnetic-dipole transitions. At atmospheric pressure, because of theline-mixing effect, the resulting band shape differs from a simple sum of the isolated lineprofiles; the profile of the single line at 118.75 GHz also deforms.The widely used Millimeter-wave Propagation Model (MPM) uses the band absorptionprofile model, which considers mixing as a pressure-proportional modification to eachline profile, or first order in the mixing effect1. In our earlier study2 it was shown thatanalysis of the band shape, taking first order mixing into account, gives a residual whichis regular and looks like second-order mixing3. However, the absorption measurements’noise level of 0.05 dB/km was insufficient for taking second-order mixing into account.In the current report we present an extended 60-GHz absorption band model based onprecise experimental profiles to increase modeling accuracy for atmospheric applications.A set of precise 60-GHz band absorption profile records was obtained by means of a res-onator spectrometer4. The resonator was set up in the climate chamber, equipped withcooling and heating elements5, which allowed running the measurements in the temper-ature range from -28 up to +60C. The noise level of the profile records is about 0.01dB/km, which allows taking second-order mixing into account. An algorithm based onthe Twomey-Tikhonov method6 was worked out to derive second-order mixing parametersfrom the experimental data and refine first-order mixing parameters, as well. The derivedmixing parameters’ temperature dependence is in good agreement with earlier studies.With the extended model, the residual error of representation of the experimental data isnot more than 1%.The work was partially supported by the Russian Foundation for Basic Researches.

1. P.W. Rosenkranz, IEEE Trans. Antenn. Prop., 23, 498 (1975).2. M. Yu. Tretyakov, M. A. Koshelev, V. V. Dorovskikh, et al., J. Mol. Spectrosc., 231,1 (2005).3. E.W. Smith, J. Chem. Phys., 74 (12), 6658 (1981).4. M.Yu. Tretyakov, A.F. Krupnov, V.V. Parshin, et al., RSI, 80(9),093106 (2009).5. D.S. Makarov, I.A. Koval, M.A. Koshelev, V.V. Parshin, M.Yu. Tretyakov, J. Mol.Spectrosc, 252, 242 (2008).6. P.W. Rosenkranz, J. Quant. Spectrosc. Radiat. Transfer, 39, 287, (1988).

Presentation mode: lectureTime required: 15 min

From atomic to molecular Bose-Einstein condensates: a physically real-izable term-crossing model for cold atom association

Ruzan SOKHOYAN and Artur ISHKHANYAN, Institute forPhysical Research of NAS of Armenia, 0203 Ashtarak-2, Armenia;Claude LEROY and Hans-Rudolf JAUSLIN, Laboratoire Inter-disciplinaire Carnot de Bourgogne, UMR-CNRS 5209, 9. av. A. Savary,21078 Dijon, France.

The Landau-Zener (LZ) modela long ago became a standard notion in quantum physics. Itdescribes a situation when two quantum states are coupled by an external field of constantamplitude and a variable frequency which is linearly changed in time. But this situationhas some drawbacks; it is unrealistic to have a constant coupling that never turns off orinfinite energies at t→ ±∞. However, there exists a model that has all the virtues of theLZ model and is free from its shortcomings. Such model is the first Demkov-Kunike (DK)quasi-linear level-crossing model of a bell-shaped pulse (vanishing at t→ ±∞) and finitedetuningb. The DK model can be considered as a physical generalization of the LZ model.We consider the basic nonlinear (NL) version of the DK problem relevant to one-colortwo-mode photoassociation of cold atomsc and sweep across a Feshbach resonanced. Weinvestigate the case when the system is initially in all-atomic state. We discuss two lim-iting cases of the NL DK problem - weak interaction limit corresponding to small peakRabi frequency, U0 << 1, and strong interaction limit occurring at high values of themaximal field intensities, U0 >> 1. The strong interaction limit is subdivided into twodistinct regimes, the large and small detuning regimesef. The main peculiarity of the pho-toassociation process in the large detuning regime is its almost non-oscillatory behavior,i.e., only weak oscillations between the atomic and molecular populations occur. On thecontrary, in the small detuning regime the evolution of the system is essentially oscillatory;high-amplitude large-frequency oscillations are observed.Using an exact third-order NL differential equation for the molecular state probability,we develop a variational approach which enables us to construct highly accurate analyticapproximations describing time dynamics of the coupled atom-molecular system in each ofthe interaction regimes. We show that the approximation describing time evolution of themolecular state probability both in the weak interaction limit and in the large detuningregime of the strong interaction limit can be written as a sum of two distinct terms; the firstone, being a solution to a limit first-order NL equation, effectively describes the processof the molecule formation while the second one, being a scaled solution to the linear DKproblemb (but now with modified parameters), models the remaining oscillations whichcome up when the process of molecule formation is over. The graphs of the approximateand numerical solutions are practically indistinguishable for almost all the time range.

aL.D. Landau, Phys. Z. Sowjetunion, 2, 46 (1932); C. Zener, Proc. R. Soc. London, Ser. A137, 696 (1932).

bN. Demkov and M. Kunike, Vestn. Leningr. Univ. Fis. Khim. 16, 39 (1969).cM. Kostrun, M. Mackie, R. Cote, and J. Javanainen, Phys. Rev. A 62, 063616 (2000).dD.J. Heinzen, R. Wynar, P.D. Drummond, and K.V. Kheruntsyan, Phys. Rev. Lett. 84, 5029

(2000).eA. Ishkhanyan, B. Joulakian and K.-A. Suominen, Euro. Phys. J. D 48, 397 (2008).fA. Ishkhanyan, R. Sokhoyan, K. Suominen, C. Leroy, H.-R. Jauslin, Euro. Phys. J. D 56, 421

(2010).

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recent developments of sub-mm wave ......and backward wave oscillator (bwo) covering the frequency...

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